[Regression] Modeler ArgumentNullException with request body parameters

Attempting to generate code for an OpenAPI 3.0 document with a multipart/form-data request body, such as the following:

openapi: '3.0.3'
info:
  title: OpenAPI 3 example with multipart/form-data request body
  version: '1.0.0'
components:
  schemas:
    ExampleFormDataBody:
      type: object
      properties:
        prop1:
          type: string
        prop2:
          type: string
paths:
  /post-example:
    post:
      operationId: postExample
      requestBody:
        content:
          multipart/form-data:
            schema:
              $ref: '#/components/schemas/ExampleFormDataBody'
      responses:
        '201':
          description: Success

Using the command autorest --v3 --csharp --input-file=openapi.yaml, produces an error such as:

AutoRest code generation utility [cli version: 3.0.6187; node: v10.17.0, max-memory: 8192 gb]
(C) 2018 Microsoft Corporation.
https://aka.ms/autorest
   Loading AutoRest core      '/home/kevin/.autorest/@autorest_core@3.0.6246/node_modules/@autorest/core/dist' (3.0.6246)
   Loading AutoRest extension '@microsoft.azure/autorest.csharp' (~2.3.79->2.3.84)
   Loading AutoRest extension '@microsoft.azure/autorest.modeler' (2.3.55->2.3.55)
FATAL: System.ArgumentNullException: Value cannot be null.
Parameter name: source
   at System.Linq.Enumerable.Select[TSource,TResult](IEnumerable1 source, Func2 selector)
   at AutoRest.Modeler.Model.RequestBody.AsParameters() in /opt/vsts/work/1/s/src/Model/RequestBody.cs:line 38
   at AutoRest.Modeler.SwaggerModeler.Unwrap(SwaggerParameter swaggerParameter) in /opt/vsts/work/1/s/src/SwaggerModeler.cs:line 452
   at AutoRest.Modeler.OperationBuilder.BuildMethodParameters(Method method) in /opt/vsts/work/1/s/src/OperationBuilder.cs:line 255
   at AutoRest.Modeler.OperationBuilder.BuildMethod(HttpMethod httpMethod, String url, String methodName, String methodGroup) in /opt/vsts/work/1/s/src/OperationBuilder.cs:line 100
   at AutoRest.Modeler.SwaggerModeler.BuildMethod(HttpMethod httpMethod, String url, String name, Operation operation) in /opt/vsts/work/1/s/src/SwaggerModeler.cs:line 404
   at AutoRest.Modeler.SwaggerModeler.Build(ServiceDefinition serviceDefinition) in /opt/vsts/work/1/s/src/SwaggerModeler.cs:line 106
   at AutoRest.Modeler.Program.<ProcessInternal>d__2.MoveNext() in /opt/vsts/work/1/s/src/Program.cs:line 60
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at NewPlugin.<Process>d__15.MoveNext()
  Error: Plugin imodeler1 reported failure.

Thanks, Kevin

[kevinoid]

I just noticed this issue also affects OpenAPI 2 documents. For example:

OpenAPI 2 example with formData parameters

swagger: '2.0'
info:
  title: OpenAPI 2 example with multipart/form-data request body
  version: 1.0.0
definitions:
  ExampleFormDataBody:
    properties:
      prop1:
        type: string
      prop2:
        type: string
    type: object
paths:
  /post-example:
    post:
      consumes:
      - multipart/form-data
      parameters:
      - in: formData
        name: prop1
        type: string
      - in: formData
        name: prop2
        type: string
      responses:
        '201':
          description: Success
      operationId: postExample

I also bisected the affected versions and found that --version:3.0.6130 works correctly while--version:3.0.6132 does not.

[UncleFirefox]

Hi, we’re also getting the additionalProperties problem doing autorest --input-file=swagger.json --output-folder=. --typescript --version=3.0.6274 anybody looking at it?